<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			body {
				height: 2000px;
				margin: 0;
				padding: 0;
			}
			
			.div {
				margin: 100px;
				width: 100px;
				height: 100px;
				background: gray;
				padding: 20px;
			}
		</style>
	</head>

	<body>
		<div id="div1" class="div">div1</div>
		
		<div id="div2" class="div">
			div2
			<button>click</button>
		</div>
	</body>
	<script type="text/javascript">
		document.getElementById('div1').onclick = function() {
			console.log('target',event.target);
			console.log('curr',event.currentTarget);
			console.log(event.target === event.currentTarget);
		}
		
		
		document.getElementById('div2').onclick = function(ev) {
			console.log('target',event.target);
			console.log('curr',event.currentTarget);
		}
		
		// 总结: 
		// 1. target是点击的元素
		// 2. currentTarent是事件绑定的元素
		// 当绑定的元素和点击的元素是一致时,target === currentTarget
		
		
	</script>
</html>